NEWLY elected state GOP Chairman Joseph Mondello has been in office for less than a week – but he’s already being accused of breaking his word to party leaders, Republican insiders charged yesterday.

Mondello, the longtime Nassau County GOP chairman, vowed last week to take the badly damaged state Republican Party out of the hands of Gov. Pataki’s widely despised political operatives, who are blamed for last month’s worst-ever-in-modern-times showing at the polls.

But the insiders charge that Mondello is ready to name John Haggerty – a longtime Pataki gofer and political “mechanic” who has angered numerous party activists, including influential GOP Sen. Serphin Maltese of Queens – to the key post of party executive director.

“Haggerty is one of the reasons we keep losing races. He’s a disaster, and his appointment will be deeply resented by Republicans who want to win elections,” a longtime senior GOP strategist bitterly told The Post.

“A lot of party people are up in arms over this and believe Mondello would be sending the absolute wrong signal if he goes ahead with this.”

Mondello, who wouldn’t deny that Haggerty is under consideration, is being leaned on heavily by Senate Majority Leader Joseph Bruno, now the strongest force in the state GOP, to pick Haggerty, the son of one-time Senate chief counsel Jack Haggerty.

“[John] Haggerty has sworn allegiance [to] Bruno, and Bruno is demanding that Mondello let him run the day-to-day party operations,” said another GOP source.

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Manhattan state Sen. Eric Schneiderman, once widely seen as the next Senate Democratic leader, will be “persona non grata” with newly selected Democratic Minority Leader Malcolm Smith of Queens, insiders say.

Schneiderman, who claimed he would easily win enough votes to succeed outgoing Minority Leader David Paterson – now the lieutenant governor-elect – is blamed by Smith for circulating supposedly damaging information about Smith’s private business dealings in hopes of derailing his campaign.

“Some reporters may love Schneiderman, but it took the votes of senators, not journalists, to make Smith the leader, and he’s going to reward those senators who stood with him,” said a source close to Smith.